Water is a sneaky substance. If you do not tell it where to go, it will go wherever it wants to. And though you might tend to think otherwise, down is not always out.
Think about the last time you went to a restaurant. You’ve probably seen a pitcher of water with a tea towel tied around the neck. You might also have been in the unfortunate circumstance to have been “baptized” by a well-meaning waiter wielding such a pitcher without said tea towel. You’ve seen first hand that even if you think you are directing water to go down a certain path, it doesn’t always obey. To be sure, some water pitchers are better engineered than others and offer less room for error, but the really regrettable part of this analogy is that it seems more attention is spent engineering water pitchers than the item most important to protecting everything tangible in your life…your roof.
Most shingle roofs do not have established water channels. What happens then, is that just like the water pitcher, the water starts to back up along the shingle edge. Physics takes over from that point and water starts to miraculously flow uphill.
Before we go on, let’s discuss the real definition of interlocking. Interlocking in our dictionary means to “lock” one piece with another. And in our world, water is not a welcome guest. Therefore, our objective is to “lock out” water. Pretty simple. Ok. Back to the story…
Precipitation will cool down a roof. Obvious, right? But the shingles still retain a bit of heat underneath. This causes a pressure differential which literally pulls the water up and under the shingle. If the shingle isn’t in a position to “lock out” the water and by its design direct the flow of the water, you can be assured that it is only a matter of time before disaster strikes. It is unfortunate that the word “interlocking” doesn’t have a regulatory agency like the FDA to govern its usage because many companies use the term way too loosely.
A Fine Metal Roof Tech interlocking shingle is set with the pointed edge facing down. This channels the water. It’s a perpetual water “traffic director” and keeps the temptation of the water to back up at bay. Shingles with a straight base set horizontally are at a much higher risk of failure.
I hear you saying, “Wait just a minute! I’ve seen your horizontal layout patterns. What gives?”
Good question. Our shingles are undeniably versatile in layout options, but as we carefully mentioned, some applications are for wall cladding only.
Now, you want to know why slates have been in use for hundreds of years and they don’t interlock, but they stay water-tight? Another great question! The answer to this proves our argument further. Check out the following gallery:
These pictures were all taken in Germany. You can clearly see that if the shape of the slate has an ambiguous water channel, the slates are set at an angle. Always. This is a fun game: On your next trip to the Oktoberfest, see if you can find any exceptions to this rule. Look all you want, but you won’t ever see any. You will, however see shapes like ours in both slate and metal. Those will be set perfectly horizontal because of their established water channel.
This is one of many reasons why our system stays water-tight and why our shingles last.